Sintered material and cutting tool including same

ABSTRACT

A sintered material includes a first material and a second material, wherein the first material is partially stabilized ZrO 2  in which 1 to 90 volume % of Al 2 O 3  is dispersed in crystal grain boundaries or crystal grains, the Al 2 O 3  is a grain having a grain size of less than or equal to 1 μm, and the second material is at least one compound selected from a group consisting of a carbide, a nitride, and a carbonitride, and 5 to 95 volume % of the second material is included in the sintered material.

TECHNICAL FIELD

The present invention relates to a sintered material and a cutting toolincluding the sintered material. The present application claims apriority based on Japanese Patent Application No. 2016-203467 filed onOct. 17, 2016, the entire content of which is incorporated herein byreference.

BACKGROUND ART

For example, as disclosed in Japanese Patent Laying-Open No. 2001-019537(Patent Literature 1), there has been known a sintered material(so-called “black ceramic”) including: one of a carbide, a nitride, acarbonitride, each of which includes at least one of Ti, Zr, Nb, and Ta,and tungsten carbide; Al₂O₃; and a Zr compound. A cutting tool employingsuch a sintered material has an excellent wear resistance, and is usedfor cutting of hardened steel, gray iron, and the like.

CITATION LIST Patent Literature

PTL 1: Japanese Patent Laying-Open No. 2001-019537

SUMMARY OF INVENTION

A sintered material according to one embodiment of the presentdisclosure includes a first material and a second material, wherein thefirst material is partially stabilized ZrO₂ in which 1 to 90 volume % ofAl₂O₃ is dispersed in crystal grain boundaries or crystal grains, theAl₂O₃ is a grain having a grain size of less than or equal to 1 μm, andthe second material is at least one compound selected from a groupconsisting of a carbide, a nitride, and a carbonitride, and 5 to 95volume % of the second material is included in the sintered material.

Further, a cutting tool according to one embodiment of the presentdisclosure includes the above-described sintered material.

DETAILED DESCRIPTION Problems to be Solved by the Present Disclosure

It has been pointed out that the sintered material disclosed in PatentLiterature 1 is chipped during cutting because respective toughnesses ofTiC and Al₂O₃ included therein are low.

In view of the above, the present disclosure has an object to provide: asintered material including at least one of a carbide, a nitride, and acarbonitride and having an excellent chipping resistance; and a cuttingtool including the sintered material.

Advantageous Effect of the Present Disclosure

According to the description above, there can be provided: a sinteredmaterial including at least one of a carbide, a nitride, and acarbonitride and having an excellent chipping resistance; and a cuttingtool including the sintered material.

DESCRIPTION OF EMBODIMENTS

First, embodiments of the present invention are listed and described.

[1] A sintered material according to one embodiment of the presentdisclosure includes a first material and a second material, wherein thefirst material is partially stabilized ZrO₂ in which 1 to 90 volume % ofAl₂O₃ is dispersed in crystal grain boundaries or crystal grains, theAl₂O₃ is a grain having a grain size of less than or equal to 1 μm, andthe second material is at least one compound selected from a groupconsisting of a carbide, a nitride, and a carbonitride, and 5 to 95volume % of the second material is included in the sintered material.With such a configuration, the sintered material can have an excellentchipping resistance.

[2] Preferably, the compound includes at least one element selected froma group consisting of a group 4 element, a group 5 element, a group 6element, and Si in a periodic table. Accordingly, the sintered materialcan have a more excellent chipping resistance.

[3] Preferably, a volume ratio, ZrO₂/(ZrO₂+Al₂O₃), in the first materialis more than or equal to 0.49. Accordingly, the sintered material canhave a further excellent chipping resistance.

[4] Preferably, the sintered material further includes a third phase,the third phase includes at least one selected from a group consistingof aluminum oxide, magnesium oxide, cerium oxide, yttrium oxide, andhafnium oxide, and less than or equal to 95 volume % of the third phaseis included in the sintered material. Accordingly, the sintered materialcan have an excellent wear resistance.

[5] A cutting tool according to one embodiment of the present disclosureincludes the above-described sintered material. With such aconfiguration, the cutting tool can have an excellent chippingresistance.

Details of Embodiments of the Present Invention

The following describes an embodiment (hereinafter, also referred to as“the present embodiment”) of the present invention more in detail.

Here, in the present specification, the expression “A to B” represents arange of lower to upper limits (i.e., more than or equal to A and lessthan or equal to B). When no unit is indicated for A and a unit isindicated only for B, the unit of A is the same as the unit of B.Moreover, when a compound or the like is expressed by a chemical formulain the present specification and an atomic ratio is not particularlylimited, it is assumed that all the conventionally known atomic ratiosare included. The atomic ratio is not necessarily limited only to one inthe stoichiometric range. In the present embodiment, a metallic elementand a nonmetallic element does not necessarily need to constitute astoichiometric composition. Examples of the metallic element includetitanium (Ti), aluminum (Al), silicon (Si), tantalum (Ta), or chromium(Cr). Examples of the nonmetallic element include nitrogen (N), oxygen(O), and carbon (C). The term “grain size” or “particle size” in thepresent specification means an average grain size or average particlesize unless otherwise particularly stated.

<<Sintered Material>>

Conventionally, it has been known that when used as a cutting tool, asintered material including at least one of a carbide, a nitride, and acarbonitride, Al₂O₃, and a Zr compound has an excellent wear resistancein high-speed cutting of centrifugal cast iron. However, since Al₂O₃ isa low-toughness material, the sintered material may be chipped when usedfor high-speed long-distance cutting.

On the other hand, according to researches of the present inventors, ahigh-toughness material has been obtained in the following manner: Al₂O₃is finely precipitated (more than or equal to 0.1 μm) in ZrO₂ grains orZrO₂ grain boundaries in a partially stabilized ZrO₂ sintered materialthat is produced through a neutralization co-precipitation method or asol-gel method, a HIP method or a SPS (pulse electric current) sinteringmethod, and that has Al₂O₃ dissolved in a solid state.

Further, the present inventors have completed the present invention byobtaining the following knowledge: chipping resistance is improvedsignificantly when fine Al₂O₃ is included and presented in a specificform within a sintered material including partially stabilized ZrO₂serving as a high-toughness material and at least one of a carbide, anitride, and a carbonitride. The chipping resistance is improvedsignificantly presumably due to the following reason: the structure ofthe partially stabilized ZrO₂ becomes tough due to the finelyprecipitated Al₂O₃, thus resulting in a synergistic effect of theresultant toughness and intrinsic characteristics of the carbide, thenitride, and the carbonitride. Such a sintered material also has anexcellent wear resistance.

A sintered material according to the present embodiment is a sinteredmaterial including a first material and a second material. The firstmaterial is partially stabilized ZrO₂ in which 1 to 90 volume % of Al₂O₃is dispersed in crystal grain boundaries or crystal grains. The Al₂O₃ isa grain having a grain size of less than or equal to 1 μm. The secondmaterial is at least one compound selected from a group consisting of acarbide, a nitride, and a carbonitride, and 5 to 95 volume % of thesecond material is included in the sintered material.

Such a sintered material according to the present embodiment may includeany other component(s) as long as the sintered material includes thefirst material and the second material. Examples of the othercomponent(s) can include, but should not be limited only to, a thirdphase and the like as described below. Moreover, such a sinteredmaterial may include an inevitable impurity as long as the sinteredmaterial exhibits a desired effect. As a matter of course, the sinteredmaterial can include only both the first material and the secondmaterial. The following describes each of the components of such asintered material.

<First Material>

The first material is partially stabilized ZrO₂ in which 1 to 90 volume% of Al₂O₃ is dispersed in crystal grain boundaries or crystal grains ofthe partially stabilized ZrO₂. The Al₂O₃ is a grain having a grain sizeof less than or equal to 1 μm.

The term “partially stabilized ZrO₂” has the conventionally knownmeaning, and refers to ZrO₂ in which cubic and tetragonal crystals arestable or metastable at a room temperature.

Examples of an oxide other than ZrO₂ and Al₂O₃ include: calcium oxide;magnesium oxide; and a rare earth oxide such as yttrium oxide. Thepartially stabilized ZrO₂ can include one or two or more of theabove-described oxides. An amount of solid solution of the oxide(s)other than ZrO₂ and Al₂O₃ is preferably about 1 to 4 mol % relative toZrO₂.

The partially stabilized ZrO₂ includes 1 to 90 volume % of Al₂O₃ withrespect to the partially stabilized ZrO₂. More preferably, 1 to 51volume % of Al₂O₃ with respect to the partially stabilized ZrO₂ isincluded therein. Accordingly, characteristics, such as high hardness,high strength, and high toughness, are obtained, whereby adifficult-to-cut steel material can be cut in high speed. When thecontent of Al₂O₃ is less than 1 volume %, the above-describedcharacteristics cannot be obtained, with the result that the chippingresistance is decreased. When the content of Al₂O₃ is more than 90volume %, the toughness is decreased significantly.

Al₂O₃ is present in a manner of being dispersed in the crystal grainboundaries or crystal grains of the partially stabilized ZrO₂. Namely,the expression “present in a manner of being dispersed” means thatfine-grained Al₂O₃ is precipitated to be dispersed in the crystal grainboundaries or the crystal grains. Hence, Al₂O₃ needs to be grains(crystal grains) each having a grain size of less than or equal to 1 μm.When the grain size of Al₂O₃ is more than 1 μm, the hardness and thetoughness are decreased. Al₂O₃ is preferably a grain having a grain sizeof less than or equal to 0.5 μm, and is more preferably a grain having agrain size of less than or equal to 0.1 μm. As the grain size issmaller, the toughness tends to be improved, so that the lower limit ofthe grain size should not be limited. However, when the grains are toofine, the toughness of the material itself tends to be decreased. Hence,the grain size of Al₂O₃ is preferably more than or equal to 0.005 μm.

Here, the grain size of Al₂O₃ is changed depending on sinteringconditions. Moreover, even under the same sintering conditions, thegrain size of Al₂O₃ varies between the case of sintering only the firstmaterial and the case of mixing and sintering the first material and thesecond material described below. Namely, comparing the grain size ofAl₂O₃ in the case of sintering only the first material with the grainsize of Al₂O₃ in the case of mixing and sintering the first material andthe second material, the latter grain size (i.e., the grain size ofAl₂O₃ in the sintered material including the second material) tends tobe a fine grain size (crystal grain size) that is approximately onetenth as small as the former grain size (i.e., the grain size of Al₂O₃in the case of only the first material), even when the same sinteringconditions (such as temperature and pressure) are applied. This ispresumably due to the following reason: since the first material and thesecond material are combined to suppress crystal grain growth of Al₂O₃,the grain size of Al₂O₃ becomes finer.

Therefore, the phenomenon in which the grain size (crystal grain size)of Al₂O₃ becomes less than or equal to 0.1 μm is a specific phenomenonthat appears when the first material and the second material are mixedand sintered. When the second material is not included, the grain sizeof Al₂O₃ does not become less than or equal to 0.1 μm (normally, thegrain size is more than 0.2 μm).

In the sintered material according to the present embodiment, thetoughness is improved significantly because Al₂O₃ is finely dispersed inthe partially stabilized ZrO₂ as described above. This is presumably dueto the structure being tough by Al₂O₃. In addition, Al₂O₃ can be presentin either or both of the crystal grain boundaries and the crystalgrains. Namely, a position of presence of Al₂O₃ is not limited to aparticular position of the partially stabilized ZrO₂.

The grain size, content (volume) and position of presence of Al₂O₃ canbe determined in accordance with the following method. Specifically, thesintered material is subjected to a CP (Cross Section Polisher) processusing an ion beam, thereby forming a smooth cross section. Next, thecross section is observed using a scanning electron microscope (SEM),thereby specifying the position of presence of Al₂O₃. Based on themicroscope image obtained by this SEM, a binarization process isperformed using image analysis software and the equivalent circlediameter and area of Al₂O₃ are calculated. The equivalent circlediameter can be regarded as the grain size. Moreover, the area can beregarded as a volume, and therefore can be regarded as the content ofAl₂O₃. In the present specification, the term “equivalent circlediameter” refers to the diameter of an imaginary circle having an areacomparable to the area of the measurement object calculated by abinarization process employing image analysis software.

The grain size (equivalent circle diameter) of Al₂O₃ is an average grainsize. This average grain size can be calculated as follows: a total often microscope images are captured from positions in which Al₂O₃ ispresent; these microscope images are subjected to a binarization processemploying image analysis software to calculate 50 equivalent circlediameters of Al₂O₃ from each of the microscope images (therefore, atotal of 500 equivalent circle diameters of Al₂O₃ are calculated by 10microscope images×50 equivalent circle diameters); and the average valuethereof is calculated. Likewise, the content (volume) of Al₂O₃ can becalculated as an average value of 500 areas of Al₂O₃ calculated from 10microscope images.

Here, a volume ratio, ZrO₂/(ZrO₂+Al₂O₃), in the first material ispreferably more than or equal to 0.49. ZrO₂/(ZrO₂+Al₂O₃) is an indexindicating the chipping resistance. As the value thereof is larger, thechipping resistance is more improved. Since ZrO₂/(ZrO₂+Al₂O₃) is morethan or equal to 0.49, the chipping resistance of the sintered materialcan be particularly improved. This is presumably due to the followingreason: with the above-described volume ratio in the first material, aratio of Al₂O₃ finely precipitated in the crystal grain boundaries orcrystal grains of the partially stabilized ZrO₂ is optimized, wherebythe structure of the partially stabilized ZrO₂ becomes tougher. Althoughthe upper limit value of the volume ratio, ZrO₂/(ZrO₂+Al₂O₃), does notneed to be defined particularly, it is preferable to set the upper limitvalue at a value, such as 0.99, at which an amount of aluminum oxidedoes not become too small.

The volume of ZrO₂ in the first material can be determined by the samemethod as the method for measuring the volume of Al₂O₃, i.e., can bedetermined in the following manner: the area thereof is measured byusing image analysis software to perform a binarization process onto areflected electron image obtained through measurement of a CP-processedsurface with a scanning electron microscope (SEM); and this area isconverted into a volume. Therefore, the volume ratio, ZrO₂/(ZrO₂+Al₂O₃),can be calculated by the following method. First, the sintered materialis subjected to a CP process using an ion beam, thereby forming a smoothcross section. The cross section is observed using a scanning electronmicroscope (SEM) to obtain a reflected electron image. This reflectedelectron image is subjected to a binarization process using imageanalysis software so as to measure respective areas of ZrO₂ and Al₂O₃.The areas are then converted into volumes.

For example, the first material can be obtained using a below-describedneutralization co-precipitation method or sol-gel method.

(Neutralization Co-Precipitation Method)

The neutralization co-precipitation method is a method including thefollowing steps A and B. Such a method is described in a paper (J. Jpn.Soc. Powder Powder Metallurgy, Vol. 60, No. 10, P428-435) published in2013, for example.

Step A is a step of mixing a zirconium salt, a yttrium salt and analuminum salt such that a volume ratio between zirconia (ZrO₂) andyttria (Y₂O₃) is 98.2:1.8 to 98.8:1.2 and a volume ratio betweenyttria-added zirconia and alumina (Al₂O₃) is 10:90 to 99:1, to therebyprepare a mixed solution. Here, yttria (Y₂O₃) is illustrated as an oxidedissolved in a solid state in zirconia (ZrO₂); however, the oxide is notlimited only to this.

Step B is a step of adding alkali to the mixed solution obtained in stepA above for neutralization, and co-precipitating zirconium, yttrium andaluminum, to thereby obtain a precipitate, and drying the precipitate,and thereafter, performing heat treatment at 650 to 750° C. for 7 to 12hours and performing calcination at 850 to 950° C. for 0.5 to 3 hours,to thereby prepare Y₂O₃ stabilized ZrO₂—Al₂O₃ solid solution powder.

Examples of the zirconium salt in step A include: zirconium oxychloride(ZrOCl₂), zirconium oxynitrate (ZrO(NO₃)₂), and the like. Examples ofthe yttrium salt include yttrium chloride (YCl₃), yttrium nitrate(Y(NO₃)₃), and the like. Examples of the aluminum salt include aluminumchloride (AlCl₃) and the like. Examples of a solvent for the mixedsolution include nitric acid, hydrochloric acid, and the like.

(Sol-Gel Method)

The sol-gel method is a method including the following step X. Such amethod is, for example, described in a paper (J. Jpn. Soc. Powder PowderMetallurgy, Vol. 58, No. 12, P727-732) published in 2011.

Step X is a step of preparing an amorphous solid solution powdercomposed of 5 to 90 mol % of Al₂O₃ and ZrO₂ having 0.3 to 1.7 mol % ofY₂O₃ added thereto (99.7 to 98.3 mol % of ZrO₂— 0.3 to 1.7 mol % ofY₂O₃) by using the sol-gel method, and calcining the obtained amorphoussolid solution powder at a temperature equal to or higher than acrystallization temperature, to thereby prepare a crystalline, partiallystabilized ZrO₂ solid solution powder.

(Other Methods)

The first material of the present embodiment can also be obtained by amethod other than the above-described two methods. That is, partiallystabilized ZrO₂ and Al₂O₃ are mixed with each other in a solvent such asethanol using a grinder such as a bead mill or a ball mill, therebyobtaining a slurry. Then, granulation is performed using this slurry,and the first material can thus be obtained. Granulation means shouldnot be particularly limited, and examples thereof include meltgranulation or spray granulation.

The strength of the granulated material (first material) obtained by theabove method can be improved by the following method:

(1) performing sintering in a heat treatment furnace (for example, at1000° C. in vacuum for 3 hours); or

(2) adding 10 mass % of a binder (a general binder such as PVB(polyvinyl butyral)) to the slurry, which is in a stage prior to thegranulated material.

As described above, the first material can be obtained by variousmethods and a method for manufacturing the first material should not beparticularly limited.

5 to 95 volume % of the first material is preferably included in thesintered material. When the ratio of the first material in the sinteredmaterial is less than 5 volume %, the wear resistance and the chippingresistance may be decreased. When the ratio of the first material in thesintered material is more than 95 volume %, the hardness may bedecreased and thus the wear resistance may be decreased. The ratio ofthe first material in the sintered material is more preferably 10 to 90volume %.

Preferably, the first material has an average grain size of 0.01 μm to 1μm. When the average grain size is smaller than 0.01 μm, aggregation islikely to occur during mixing with other powders, and thus, poorsintering tends to occur. When the average grain size exceeds 1 μm, thestrength tends to decrease due to grain growth during sintering. Theaverage grain size is more preferably 0.1 to 0.5 μm.

The average grain size of the first material can be determined by thesame method as the method for determining the grain size of Al₂O₃.Specifically, the CP process is performed on the sintered material withan ion beam, to thereby form a smooth cross section. Then, the crosssection is observed with the scanning electron microscope (SEM). By abinarization process with the image analysis software, an equivalentcircle diameter of the first material is calculated, and this equivalentcircle diameter can be defined as the average particle size.

Further, the compositions and contents (volumes) of the components ofthe sintered material of the present embodiment, in addition to thisfirst material, can be determined by a reflected electron image obtainedby measuring the CP-processed surface with the scanning electronmicroscope (SEM), EDX (energy dispersive X-ray analysis), or Augerelectron spectroscopy analysis.

For example, the volume of the first material can be determined by thesame method as the method for measuring each of the volumes of ZrO₂ andAl₂O₃, i.e., can be determined by measuring the area of the firstmaterial by using image analysis software to perform a binarizationprocess onto a reflected electron image obtained through measurement ofa CP-processed surface with a scanning electron microscope (SEM).

<Second Material>

As described above, the sintered material according to the presentembodiment includes the first material and the second material. Thesecond material is at least one compound selected from a groupconsisting of a carbide, a nitride, and a carbonitride, and 5 to 95volume % of the second material is included in the sintered material.

That is, the second material is preferably included in the sinteredmaterial at a ratio of 5 to 95 volume %. When the ratio of the secondmaterial in the sintered material is less than 5 volume %, the hardnessmay be decreased to result in a decreased wear resistance. When theratio of the second material in the sintered material becomes more than95 volume %, the chipping resistance may be decreased. The content ofthe second material in the sintered material is more preferably 10 to 90volume %. The content of the second material can be determined by thesame measurement method as the method for measuring the content of thefirst material.

The above-described compound serving as the second material ispreferably at least one element selected from a group consisting of agroup 4 element, a group 5 element, a group 6 element in the periodictable, and Si. That is, the above-described compound is preferably oneof a carbide, a nitride and a carbonitride each including at least oneelement selected from a group consisting of a group 4 element (Ti, Zr,Hf, or the like), a group 5 elements (V, Nb, Ta, or the like), a group 6element (Cr, Mo, W, or the like) in the periodic table, and Si.Accordingly, the sintered material according to the present embodimentcan have a more excellent chipping resistance.

Specific examples of the carbide serving as the second material caninclude TiC, ZrC, HfC, NbC, TaC, SiC, Mo₂C, WC, and the like. Examplesof the nitride can include TiN, ZrN, HfN, NbN, TaN, Si₃N₄, CrN, and thelike. Examples of the carbonitride can include TiCN, ZrCN, HfCN, NbCN,TaCN, and the like.

<Third Phase>

The sintered material according to the present embodiment can furtherinclude the third phase. The third phase is preferably at least oneselected from a group consisting of aluminum oxide, magnesium oxide,cerium oxide, yttrium oxide, and hafnium oxide. Further, less than orequal to 95 volume % of the third phase is preferably included in thesintered material.

Sinterability of the sintered material according to the presentembodiment is improved when the sintered material contains, as the thirdphase, less than or equal to 95 volume % of at least one selected fromthe group consisting of aluminum oxide, magnesium oxide, cerium oxide,yttrium oxide, and hafnium oxide. Accordingly, an excellent wearresistance can be obtained while achieving the effect in which thestructure of the partially stabilized ZrO₂ becomes tough due to finelyprecipitated Al₂O₃. The content of the third phase is more preferably 0to 60 volume %.

The third phase preferably has an average grain size of 0.05 to 5 μm.When the average grain size is less than 0.05 μm, poor sintering tendsto occur due to aggregation when mixed with other powders. When theaverage grain size is more than 5 μm, the strength tends to be decreaseddue to grain growth during sintering.

The average grain size of the third phase can be determined by the samemeasurement method as the method for measuring the grain size of each ofAl₂O₃ and the first material. Further, the content of the third phasecan be also determined by the same measurement method as the method formeasuring the content of the first material.

<Function>

According to the above, in the sintered material according to thepresent embodiment, the structure of the partially stabilized ZrO₂serving as the first material becomes tough by Al₂O₃ dispersed andfinely precipitated in the crystal grain boundaries or crystal grains.The chipping resistance can be improved significantly by the synergisticeffect of the characteristics of such a first material and the intrinsiccharacteristics of the carbide, nitride, or carbonitride, each of whichserves as the second material. Further, the sintered material accordingto the present embodiment can also have an excellent wear resistance.

<<Method for Manufacturing Sintered Material>>

The sintered material according to the present embodiment can bemanufactured by a conventionally known manufacturing method, and themanufacturing method should not be particularly limited.

For example, the first material, the second material and the othercomponent(s) (such as particles of the third phase) are mixed as rawmaterials using a bead mill, a ball mill or the like. Next, sintering isperformed for 10 minutes to 60 minutes at a temperature of 1300° C. to1600° C. and a pressure of 10 MPa to 7 GPa, thereby obtaining thesintered material. The pressure in the sintering is preferably 4 GPa to7 GPa. Although a sintering method is not particularly limited, sparkplasma sintering (SPS), hot press, ultra-high pressure sintering, or thelike can be used.

<<Cutting Tool>>

Since the sintered material according to the present embodiment exhibitsthe characteristics such as excellent chipping resistance and wearresistance, the sintered material according to the present embodiment issuitably used in a cutting tool and the like. Namely, a cutting toolaccording to the present embodiment includes the above-describedsintered material.

Examples of the cutting tool include a drill, an end mill, an indexablecutting insert for drill, an indexable cutting insert for end mill, anindexable cutting insert for milling, an indexable cutting insert forturning, a metal saw, a gear cutting tool, a reamer, a tap, a cuttingbite, and the like.

The above cutting tool may be entirely constituted of the sinteredmaterial of the present embodiment, or may be partially (for example,edge portion) constituted of the sintered material of the presentembodiment. A coating film may be formed on a surface of the cuttingtool.

Examples

While the present invention will be described in more detail hereinafterwith reference to Examples, the present invention is not limitedthereto.

<<Sintered Material Including Carbide as Second Material: Samples A1 toA48>>

As a raw material, the first material produced in the below-describedprocedure (neutralization co-precipitation method) was prepared. Thesecond material was prepared as commercially available carbide powder.Further, in each of predetermined samples, a commercially availablepowder of a raw material to serve as the third phase was prepared asrequired.

<Samples A1 to A26>

Sintered materials of samples A1 to A26 are produced as follows.

(Production of First Material (Precursor))

As described above, the first material (precursor) can be produced bythe following method based on the paper (J. Jpn. Soc. Powder PowderMetallurgy, Vol. 60, No. 10, P428-435) published in 2013.

Specifically, first, zirconium oxychloride (ZrOCl₂. 8H₂O), aluminumchloride (AlCl₃), and yttrium chloride (YCl₃) are added to water toprepare a mixed aqueous solution such that a volume ratio of ZrO₂ andY₂O₃ satisfies “ZrO₂:Y₂O₃=98.5:1.5” and a molar ratio of ZrO₂ havingY₂O₃ added thereto and Al₂O₃ satisfies “(ZrO₂ having Y₂O₃ addedthereto):Al₂O₃=75:25”.

Next, an aqueous ammonia solution is added to this mixed aqueoussolution to co-precipitate Zr, Y, and Al through simultaneousneutralization, and the obtained precipitate is filtered, is washed bywater, and is dried, thereby preparing amorphous hydrated zirconia (75mol % (98.5 mol % of ZrO₂— 1.5 mol % of Y₂O₃)—25 mol % of Al₂O₃ solidsolution powder.

The solid solution powder obtained in the above is calcined(heat-treated) under the conditions of 700° C., in the air and 9 hours,and is further calcined at 900° C. for 1 hour, to thereby obtain acrystalline ZrO₂ powder (in which Al₂O₃ and Y₂O₃ are dissolved in thesolid state) which is the first material (precursor). This firstmaterial (precursor) is partially stabilized ZrO₂ in which 30 volume %of Al₂O₃ is dissolved in the solid state with respect to the whole ofthe first material. Here, in Tables 1 to 5 below, “ATZ (aluminatoughened zirconia)” is described to represent the partially stabilizedZrO₂ in which Al₂O₃ serving as the first material is dissolved in thesolid state.

Here, in each of samples A8, A15, and A22 of samples A1 to A26, asdescribed below, instead of using the first material (precursor)produced by the above-described method, a commercially availablepartially stabilized ZrO₂ powder (Trademark: “TZ-3Y” provided by TOSOH;average particle size of 45 nm) in which Al₂O₃ was not dissolved in thesolid state was prepared to be used.

(Preparation of Second Material)

For the second material, a commercially available carbide powder wasprepared. Specifically, as the second material, the following materialswere prepared: TiC (grade: TiC-01; provided by Japan New Metals); ZrC(grade: ZrC—F; provided by Japan New Metals); NbC (grade: NbC; providedby Japan New Metals); TaC (grade: TaC; provided by Japan New Metals);SiC (grade: SII02PB; provided by Kojundo Chemical Laboratory); Mo₂C(grade: Mo₂C; provided by Japan New Metals); and WC (grade: WWI14PBWC;provided by Kojundo Chemical Laboratory). The particle size of thesecond material was 2 μm.

Then, the first material (precursor) and the second material constitutedof the raw material powder shown in Table 1 were mixed using a ball millto attain a blending amount (volume %) shown in Table 1, therebyobtaining a mixture of each sample. Regarding each of samples A8, A15,and A22, a commercially available partially stabilized ZrO₂ powder inwhich Al₂O₃ was not dissolved in the solid state was mixed with thepowder serving as the raw material of the second material using a ballmill so as to attain a blending amount (volume %) shown in Table 1,thereby obtaining each mixture.

Next, the mixtures of samples A1 to A6 and A8 to A26 were sintered for15 minutes at a pressure of 7 GPa and a sintering temperature of 1400°C., thereby obtaining sintered materials of samples A1 to A6 and A8 toA26. The mixture of sample A7 was sintered for 15 minutes at a pressureof 7 GPa and a sintering temperature of 1700° C., thereby obtaining asintered material of sample A7.

Each of the sintered materials of samples A1 to A26 was subjected to aCP process as described above, and a cross section thereof was observedwith the SEM, to thereby identify a position of presence of Al₂O₃ in thefirst material. In addition, by a binarization process with imageanalysis software (trademark: “WinROOF ver. 6.5.3” provided by MitaniCorporation), an equivalent circle diameter (grain size) and a contentof Al₂O₃ were calculated. As a result, it was confirmed that in each ofsamples A1 to A6, A9 to A14, A16 to A21, and A23 to A26, the grain sizeof Al₂O₃ was 0.05 μm, and the content thereof coincided with that of theraw material (30 volume %; the position of presence thereof was in thecrystal grain boundaries or the crystal grains). In the sinteredmaterial of sample A7, the content of Al₂O₃ coincided with that of theraw material; however, the grain size of Al₂O₃ was 2 μm. In each of thesintered materials of samples A1 to A6, A9 to A14, A16 to A21, and A23to A26, the average grain size of the first material was 0.15 μm. Ineach of the sintered materials of samples A8, A15, and A22, the averagegrain size of the partially stabilized ZrO₂ was 0.045 μm. In thesintered material of sample A7, the average grain size of the firstmaterial was 2.5 μm. Further, in each of the sintered materials ofsamples A1 to A26, the average grain size of the second materialcoincided with the average particle size of the raw material.

Then, in each of the sintered materials of samples A1 to A26, areflected electron image obtained by measuring a CP-processed surfaceusing a scanning electron microscope (SEM), or an elemental analysis byAuger electron spectroscopy was employed to identify the region of thefirst material or partially stabilized ZrO₂ in which Al₂O₃ was notdissolved in the solid state, and the region of the second material.Then, respective areas thereof were measured by a binarization processwith the above-described image analysis software. Accordingly, it couldbe confirmed that: each sintered material included the first material orthe partially stabilized ZrO₂ in which Al₂O₃ was not dissolved in thesolid state, and the second material; and the ratio of these coincidedwith the ratio of the raw materials.

<Samples A27 to A38>

Each of sintered materials of samples A27 to A38 is produced as follows.

(Production of First Material (Precursor) Used for Each of Samples A27,A31, and A35)

The first material (precursor) can be produced in accordance with thesame method as the method for producing the first material (precursor)used for sample A1 except for the following points.

That is, in the production of the first material (precursor) used foreach of samples A27, A31, and A35, a mixed aqueous solution is preparedsuch that a molar ratio of ZrO₂ having Y₂O₃ added thereto and Al₂O₃satisfies “(ZrO₂ having Y₂O₃ added thereto):Al₂O₃=5:95”. Further, anamorphous hydrated zirconia solid solution powder obtained from thismixed aqueous solution is prepared such that a molar ratio of ZrO₂having Y₂O₃ added thereto and Al₂O₃ satisfies 5 mol % (98.5 mol % ZrO₂—1.5 mol % Y₂O₃)—95 mol % Al₂O₃.

The produced first material (precursor) used for each of samples A27,A31, and A35 is partially stabilized ZrO₂ in which 96 volume % of Al₂O₃is dissolved in the solid state with respect to the whole of the firstmaterial.

(Production of First Material (Precursor) Used for Each of Samples A28,A32, and A36)

The first material (precursor) can be produced in accordance with thesame method as the method for producing the first material (precursor)used for sample A1 except for the following points.

That is, in the production of the first material (precursor) used foreach of samples A28, A32, and A36, a mixed aqueous solution is preparedsuch that a molar ratio of ZrO₂ having Y₂O₃ added thereto and Al₂O₃satisfies “(ZrO₂ having Y₂O₃ added thereto):Al₂O₃=15:85”. Further, anamorphous hydrated zirconia solid solution powder obtained from thismixed aqueous solution is prepared such that a molar ratio of ZrO₂having Y₂O₃ added thereto and Al₂O₃ satisfies 15 mol % (98.5 mol % ZrO₂—1.5 mol % Y₂O₃)—85 mol % Al₂O₃.

The produced first material (precursor) used for each of samples A28,A32, and A36 is partially stabilized ZrO₂ in which 88 volume % of Al₂O₃is dissolved in the solid state with respect to the whole of the firstmaterial.

(Production of First Material (Precursor) Used for Each of Samples A29,A33, and A37)

The first material (precursor) can be produced in accordance with thesame method as the method for producing the first material (precursor)used for sample A1 except for the following points.

That is, in the production of the first material (precursor) used foreach of samples A29, A33, and A37, a mixed aqueous solution is preparedsuch that a molar ratio of ZrO₂ having Y₂O₃ added thereto and Al₂O₃satisfied “(ZrO₂ having Y₂O₃ added thereto):Al₂O₃=55:45”. Further, anamorphous hydrated zirconia solid solution powder obtained from thismixed aqueous solution is prepared such that a molar ratio of ZrO₂having Y₂O₃ added thereto and Al₂O₃ satisfies 55 mol % (98.5 mol % ZrO₂—1.5 mol % Y₂O₃)—45 mol % Al₂O₃.

The produced first material (precursor) used for each of samples A29,A33, and A37 is partially stabilized ZrO₂ in which 51 volume % of Al₂O₃is dissolved in the solid state with respect to the whole of the firstmaterial.

(Production of First Material (Precursor) Used for Each of Samples A30,A34, and A38)

The first material (precursor) can be produced in accordance with thesame method as the method for producing the first material (precursor)used for sample A1 except for the following points.

That is, in the production of the first material (precursor) used foreach of samples A30, A34, and A38, a mixed aqueous solution is preparedsuch that a molar ratio of ZrO₂ having Y₂O₃ added thereto and Al₂O₃satisfies “(ZrO₂ having Y₂O₃ added thereto):Al₂O₃=99.5:0.5”. Further, anamorphous hydrated zirconia solid solution powder obtained from thismixed aqueous solution is prepared such that a molar ratio of ZrO₂having Y₂O₃ added thereto and Al₂O₃ satisfies 99.5 mol % (98.5 mol %ZrO₂— 1.5 mol % Y₂O₃)—0.5 mol % Al₂O₃.

The produced first material (precursor) used for each of samples A30,A34, and A38 is partially stabilized ZrO₂ in which 0.6 volume % of Al₂O₃is dissolved in the solid state with respect to the whole of the firstmaterial.

(Preparation of Second Material)

For the second material, a commercially available carbide powder wasprepared. Specifically, as the second material, TiC (grade: TiC-01;provided by Japan New Metals), ZrC (grade: ZrC—F; provided by Japan NewMetals), and WC (grade: WWI14PBWC; provided by Kojundo ChemicalLaboratory) were prepared.

Then, the first material (precursor) was mixed with the second materialconstituted of the raw material powder shown in Table 2 using a ballmill so as to attain a blending amount (volume %) shown in Table 2,thereby obtaining a mixture of each sample.

Next, the mixtures of samples A27 to A38 were sintered for 15 minutes ata pressure of 7 GPa and a sintering temperature of 1400° C., therebyobtaining sintered materials of samples A27 to A38.

Each of the sintered materials of samples A27 to A38 was subjected to aCP process as described above, and a cross section thereof was observedwith the SEM, to thereby identify a position of presence of Al₂O₃ in thefirst material. In addition, by a binarization process with imageanalysis software (trademark: “WinROOF ver. 6.5.3” provided by MitaniCorporation), an equivalent circle diameter (grain size) and a contentof Al₂O₃ were calculated. As a result, it was confirmed that in each ofsamples A27 to A38, the grain size of Al₂O₃ was 0.05 μm, and the contentthereof coincided with that of the raw material (30 volume %; theposition of presence thereof was in the crystal grain boundaries or thecrystal grains). In the sintered material of each of samples A27 to A38,the average grain size of the first material was 0.15 μm. Further, ineach of the sintered materials of samples A27 to A38, the average grainsize of the second material coincided with the average particle size ofthe raw material.

Then, in each of the sintered materials of samples A27 to A38, areflected electron image obtained by measuring a CP-processed surfaceusing a scanning electron microscope (SEM), or an elemental analysis byAuger electron spectroscopy was employed to identify the region of thefirst material and the region of the second material. Then, respectiveareas thereof were measured by a binarization process with theabove-described image analysis software. Accordingly, it could beconfirmed that: each sintered material included the first material andthe second material; and the ratio of the first material and the secondmaterial coincided with the ratio of the raw materials.

<Samples A39 to A48>

Each of sintered materials of samples A39 to A48 is produced as follows.

(Production of First Material (Precursor) Used for Each of Samples A39to A45)

The first material (precursor) can be produced in accordance with thesame method as the method for producing the first material (precursor)used for sample A1. This first material (precursor) is partiallystabilized ZrO₂ in which 30 volume % of Al₂O₃ is dissolved in the solidstate with respect to the whole of the first material.

Here, in each of samples A46 to A48, as described below, instead ofusing the first material (precursor) produced by the above-describedmethod, a commercially available partially stabilized ZrO₂ powder(Trademark: “TZ-3Y” provided by TOSOH; average particle size of 45 nm)in which Al₂O₃ was not dissolved in the solid state was prepared to beused.

(Preparation of Second Material)

For the second material, a commercially available carbide powder wasprepared. Specifically, as the second material, TiC (grade: TiC-01;provided by Japan New Metals), ZrC (grade: ZrC—F; provided by Japan NewMetals), and WC (grade: WWI14PBWC; provided by Kojundo ChemicalLaboratory) were prepared. The particle size of the second material was2 μm.

(Preparation of Third Phase)

For the raw material of the third phase, the following commerciallyavailable powders were prepared: Al₂O₃ powder (trademark: “TM-DAR”provided by Taimei Chemicals; average particle size of 0.1 μm); MgOpowder (trademark: “FNM-G” provided by Tateho Chemical Industries;average particle size of 0.5 μm); Ce₂O powder (trademark: “CE005PB”provided Kojundo Chemical Laboratory; average particle size of 0.2 μm);Y₂O₃ powder (trademark: “YY003PB” provided by Kojundo ChemicalLaboratory; average particle size of 0.4 μm); and HfO₂ powder(trademark: “HF001PB” provided by Kojundo Chemical Laboratory; averageparticle size of 2 μm).

Then, the first material (precursor), the second material constituted ofthe raw material powder shown in Table 2, and the third phaseconstituted of the raw material powder shown in Table 2 were mixed usinga ball mill so as to attain a blending amount (volume %) shown in Table2, thereby obtaining a mixture of each sample. For each of samples A46to A48, a commercially available partially stabilized ZrO₂ powder inwhich Al₂O₃ was not dissolved in the solid state, the powder serving asthe raw material of the second material, and the powder serving as theraw material of the third phase were mixed using a ball mill so as toattain a blending amount (volume %) shown in Table 2, thereby obtainingeach mixture.

Next, the mixtures of samples A39 to A48 were sintered for 15 minutes ata pressure of 7 GPa and a sintering temperature of 1400° C., therebyobtaining sintered materials of samples A39 to A48.

Each of the sintered materials of samples A39 to A48 was subjected to aCP process as described above, and a cross section thereof was observedwith the SEM, to thereby identify a position of presence of Al₂O₃ in thefirst material. In addition, by a binarization process with imageanalysis software (trademark: “WinROOF ver. 6.5.3” provided by MitaniCorporation), an equivalent circle diameter (grain size) and a contentof Al₂O₃ were calculated. As a result, it was confirmed that in each ofthe sintered materials of samples A39 to A45, the grain size of Al₂O₃was 0.05 μm, and the content thereof coincided with that of the rawmaterial (30 volume %; the position of presence thereof was in thecrystal grain boundaries or the crystal grains). In each of the sinteredmaterials of samples A39 to A45, the average grain size of the firstmaterial was 0.15 μm. In each of the sintered materials of samples A46to A48, the average grain size of the partially stabilized ZrO₂ was0.045 μm. Further, in each of the sintered materials of samples A39 toA48, the average grain size of the second material coincided with theaverage particle size of the raw material.

Then, in each of the sintered materials of samples A39 to A48, areflected electron image obtained by measuring a CP-processed surfaceusing a scanning electron microscope (SEM), or an elemental analysis byAuger electron spectroscopy was employed to identify the region of thefirst material or partially stabilized ZrO₂ in which Al₂O₃ was notdissolved in the solid state, the region of the second material, and theregion of the third phase. Then, respective areas thereof were measuredby a binarization process with the above-described image analysissoftware. Accordingly, it could be confirmed that: each sinteredmaterial included the first material or partially stabilized ZrO₂ inwhich Al₂O₃ was not dissolved in the solid state, the second material,and the third phase; and the ratio of these coincided with the ratio ofthe raw materials.

TABLE 1 First Material ATZ ATZ ATZ ATZ ATZ 30 vol % ATZ Sample 96 vol %88 vol % 51 vol % 30 vol % Al₂O₃ 0.6 vol % Second Material No. Al₂O₃Al₂O₃ Al₂O₃ Al₂O₃ grain size 2 μm Al₂O₃ ZrO₂ TiC ZrC NbC TaC A1 — — —  4— — — 96 — — — A2 — — — 10 — — — 90 — — — A3 — — — 40 — — — 60 — — — A4— — — 70 — — — 30 — — — A5 — — — 90 — — — 10 — — — A6 — — — 96 — — — 4 —— — A7 — — — — 70 — — 30 — — — A8 — — — — — — 70 30 — — — A9 — — —  4 —— — — 96 — — A10 — — — 10 — — — — 90 — — A11 — — — 40 — — — — 60 — — A12— — — 70 — — — — 30 — — A13 — — — 90 — — — — 10 — — A14 — — — 96 — — — — 4 — — A15 — — — — — — 70 — 30 — — A16 — — —  4 — — — — — — — A17 — — —10 — — — — — — — A18 — — — 40 — — — — — — — A19 — — — 70 — — — — — — —A20 — — — 90 — — — — — — — A21 — — — 96 — — — — — — — A22 — — — — — — 70— — — — A23 — — — 40 — — — — — 60 — A24 — — — 40 — — — — — — 60 A25 — —— 40 — — — — — — — A26 — — — 40 — — — — — — — Chipping Wear State AfterSample Second Material Third Phase Amount 10-km No. Mo₂C SiC WC Al₂O₃MgO Ce₂O Y₂O₃ HfO₂ (μm) Processing Notes A1 — — — — — — — — 100 C TooLarge Amount of TiC A2 — — — — — — — — 109 B A3 — — — — — — — — 111 A A4— — — — — — — — 122 A A5 — — — — — — — — 134 A A6 — — — — — — — — 155 CToo Small Amount of TiC A7 — — — — — — — — 125 C Coarse Al₂O₃ A8 — — — —— — — — 134 C No ATZ A9 — — — — — — — — 109 C Too Large Amount of ZrCA10 — — — — — — — — 119 B A11 — — — — — — — — 122 A A12 — — — — — — — —131 A A13 — — — — — — — — 145 A A14 — — — — — — — — 162 C Too SmallAmount of ZrC A15 — — — — — — — — 147 C No ATZ A16 — — 96 — — — — — 120C Too Large Amount of WC A17 — — 90 — — — — — 132 C A18 — — 60 — — — — —130 A A19 — — 30 — — — — — 145 A A20 — — 10 — — — — — 153 A A21 — —  4 —— — — — 168 C Too Small Amount of WC A22 — — 30 — — — — — 155 C No ATZA23 — — — — — — — — 151 B A24 — — — — — — — — 146 B A25 60 — — — — — — —167 B A26 — 60 — — — — — — 153 B

TABLE 2 First Material ATZ ATZ ATZ ATZ ATZ 30 vol % ATZ Sample 96 vol %88 vol % 51 vol % 30 vol % Al₂O₃ 0.6 vol % Second Material No. Al₂O₃Al₂O₃ Al₂O₃ Al₂O₃ Grain Size 2 μm Al₂O₃ ZrO₂ TiC ZrC NbC TaC A27 40 — —— — — — 60 — — — A28 — 40 — — — — — 60 — — — A29 — — 40 — — — — 60 — — —A30 — — — — — 40 — 60 — — — A31 40 — — — — — — — 60 — — A32 — 40 — — — —— — 60 — — A33 — — 40 — — — — — 60 — — A34 — — — — — 40 — — 60 — — A3540 — — — — — — — — — — A36 — 40 — — — — — — — — — A37 — — 40 — — — — — —— — A38 — — — — — 40 — — — — — A39 — — — 10 — — — 30 — — — A40 — — — 10— — — — 30 — — A41 — — — 10 — — — — — — — A42 — — — 10 — — — 30 — — —A43 — — — 10 — — — 30 — — — A44 — — — 10 — — — 30 — — — A45 — — — 10 — —— 30 — — — A46 — — — — — — 10 30 — — — A47 — — — — — — 10 — 30 — — A48 —— — — — — 10 — — — — Chipping Wear State After Sample Second MaterialThird Phase Amount 10-km No. Mo₂C SiC WC Al₂O₃ MgO Ce₂O Y₂O₃ HfO₂ (μm)Processing Notes A27 — — — — — — — — 100 C Too Large Amount of Al₂O₃ A28— — — — — — — — 103 B A29 — — — — — — — — 106 A A30 — — — — — — — — 119C Too Small Amount of Al₂O₃ A31 — — — — — — — — 107 C Too Large Amountof Al₂O₃ A32 — — — — — — — — 110 B A33 — — — — — — — — 115 A A34 — — — —— — — — 122 C Too Small Amount of Al₂O₃ A35 — — 60 — — — — — 112 C TooLarge Amount of Al₂O₃ A36 — — 60 — — — — — 116 B A37 — — 60 — — — — —122 A A38 — — 60 — — — — — 130 C Too Small Amount of Al₂O₃ A39 — — — 60— — — — 99 A A40 — — — 60 — — — — 105 A A41 — — 30 60 — — — — 112 A A42— — — — 60 — — — 131 B A43 — — — — — 60 — — 135 B A44 — — — — — — 60 —134 B A45 — — — — — — — 60 129 B A46 — — — 60 — — — — 122 C No ATZ A47 —— — 60 — — — — 135 C No ATZ A48 — — 30 60 — — — — 156 C No ATZ

<<Sintered Material Including Carbonitride as Second Material: SamplesB1 to B32>>

As a raw material, the first material produced in the below-describedprocedure (neutralization co-precipitation method) was prepared. Thesecond material was a carbonitride, and various types of materials wereprepared therefor using a below-described method. Further, in each ofpredetermined samples, a commercially available powder of a raw materialto serve as the third phase was prepared as required.

<Samples B1 to B16>

Sintered materials of samples B1 to B16 are produced as follows.

(Production of First Material (Precursor))

The first material (precursor) can be produced in accordance with thesame method as the method for producing the first material (precursor)used for sample A1. This first material (precursor) is partiallystabilized ZrO₂ in which 30 volume % of Al₂O₃ is dissolved in the solidstate with respect to the whole of the first material.

Here, in each of samples B7 and B14 of samples B1 to B16, as describedbelow, instead of using the first material (precursor) produced by theabove-described method, a commercially available partially stabilizedZrO₂ powder (Trademark: “TZ-3Y” provided by TOSOH; average particle sizeof 45 nm) in which Al₂O₃ was not dissolved in the solid state wasprepared to be used.

(Preparation of Second Material)

The second material was prepared by obtaining a carbonitride powderusing the following method. Specifically, TiCN was mixed with TiC(grade: TiC-01; provided by Japan New Metals) and TiN (grade: TiN-01;provided by Japan New Metals) using a ball mill or a bead mill, therebyobtaining a mixture. ZrCN was mixed with ZrC (grade: ZrC—F; provided byJapan New Metals) and ZrN (grade: ZrN-01; provided by Japan New Metals)using a ball mill or a bead mill, thereby obtaining a mixture.

NbCN was mixed with NbC (grade: NbC; provided by Japan New Metals) andNbN (grade: NbN-0; provided by Japan New Metals) using a ball mill or abead mill, thereby obtaining a mixture. TaCN was mixed with TaC (grade:TaC; provided by Japan New Metals) and TaN (grade: TaN-0; provided byJapan New Metals) using a ball mill or a bead mill, thereby obtaining amixture.

Then, each mixture was subjected to a heat treatment at 2000° C. in anAr atmosphere within a carbon furnace, and the heat-treated material wasthen pulverized using a carbide stick and a mill, thereby obtaining eachcarbonitride powder.

Then, the first material (precursor) was mixed with the second materialconstituted of the raw material powder shown in Table 3 using a ballmill so as to attain a blending amount (volume %) shown in Table 3,thereby obtaining a mixture of each sample. For each of samples B7 andB14, a commercially available partially stabilized ZrO₂ powder in whichAl₂O₃ was not dissolved in the solid state was mixed with a powderserving as the raw material of the second material using a ball mill soas to attain a blending amount (volume %) shown in Table 3, therebyobtaining a mixture.

Next, the mixtures of samples B1 to B16 were sintered for 15 minutes ata pressure of 7 GPa and a sintering temperature of 1400° C., therebyobtaining sintered materials of samples B1 to B16.

Each of the sintered materials of samples B1 to B16 was subjected to aCP process as described above, and a cross section thereof was observedwith the SEM, to thereby identify a position of presence of Al₂O₃ in thefirst material. In addition, by a binarization process with imageanalysis software (trademark: “WinROOF ver. 6.5.3” provided by MitaniCorporation), an equivalent circle diameter (grain size) and a contentof Al₂O₃ were calculated. As a result, it was confirmed that in thesintered material of each of samples B1 to B6, B8 to B13, B15 and B16,the grain size of Al₂O₃ was 0.05 μm, and the content thereof coincidedwith that of the raw material (30 volume %; the position of presencethereof was in the crystal grain boundaries or the crystal grains). Ineach of the sintered materials of samples B1 to B6, B8 to B13, B15 andB16, the average grain size of the first material was 0.15 μm. In eachof the sintered materials of samples B7 and B14, the average grain sizeof the partially stabilized ZrO₂ was 0.1 μm. Further, in each of thesintered materials of samples B1 to B16, the average grain size of thesecond material coincided with the average particle size of the rawmaterial.

Then, in each of the sintered materials of samples B1 to B16, areflected electron image obtained by measuring a CP-processed surfaceusing a scanning electron microscope (SEM), or an elemental analysis byAuger electron spectroscopy was employed to identify the region of thefirst material or partially stabilized ZrO₂ in which Al₂O₃ was notdissolved in the solid state, and the region of the second material.Then, respective areas thereof were measured by a binarization processwith the above-described image analysis software. Accordingly, it couldbe confirmed that: each sintered material included the first material orthe partially stabilized ZrO₂ in which Al₂O₃ was not dissolved in thesolid state, and the second material; and the ratio of these coincidedwith the ratio of the raw materials.

<Samples B17 to B24>

The sintered materials of samples B17 to B24 are produced as follows.

(Production of First Material (Precursor) Used for Each of Samples B17and B21)

The first material (precursor) can be produced in accordance with thesame method as the method for producing the first material (precursor)used for sample A27. This first material (precursor) is partiallystabilized ZrO₂ in which 96 volume % of Al₂O₃ is dissolved in the solidstate with respect to the whole of the first material.

(Production of First Material (Precursor) Used for Each of Samples B18and B22)

The first material (precursor) can be produced in accordance with thesame method as the method for producing the first material (precursor)used for sample A28. This first material (precursor) is partiallystabilized ZrO₂ in which 88 volume % of Al₂O₃ is dissolved in the solidstate with respect to the whole of the first material.

(Production of First Material (Precursor) Used for Each of Samples B19and B23)

The first material (precursor) can be produced in accordance with thesame method as the method for producing the first material (precursor)used for sample A29. This first material (precursor) is partiallystabilized ZrO₂ in which 51 volume % of Al₂O₃ is dissolved in the solidstate with respect to the whole of the first material.

(Production of First Material (Precursor) Used for Each of Samples B20and B24)

The first material (precursor) can be produced in accordance with thesame method as the method for producing the first material (precursor)used for sample A30. This first material (precursor) is partiallystabilized ZrO₂ in which 0.6 volume % of Al₂O₃ is dissolved in the solidstate with respect to the whole of the first material.

(Preparation of Second Material)

The second material was prepared by obtaining a carbonitride powderusing the following method. Specifically, TiCN was mixed with TiC(grade: TiC-01; provided by Japan New Metals) and TiN (grade: TiN-01;provided by Japan New Metals) using a ball mill or a bead mill, therebyobtaining a mixture. ZrCN was mixed with ZrC (grade: ZrC—F; provided byJapan New Metals) and ZrN (grade: ZrN-01; provided by Japan New Metals)using a ball mill or a bead mill, thereby obtaining a mixture.

Then, each mixture was subjected to a heat treatment at 2000° C. in anAr atmosphere within a carbon furnace, and the heat-treated material wasthen pulverized using a carbide stick and a mill, thereby obtaining eachcarbonitride powder.

Then, the first material (precursor) was mixed with the second materialconstituted of the raw material powder shown in Table 3 using a ballmill so as to attain a blending amount (volume %) shown in Table 3,thereby obtaining a mixture of each sample.

Next, the mixtures of samples B17 to B24 were sintered for 15 minutes ata pressure of 7 GPa and a sintering temperature of 1400° C., therebyobtaining sintered materials of samples B17 to B24.

Each of the sintered materials of samples B17 to B24 was subjected to aCP process as described above, and a cross section thereof was observedwith the SEM, to thereby identify a position of presence of Al₂O₃ in thefirst material. In addition, by a binarization process with imageanalysis software (trademark: “WinROOF ver. 6.5.3” provided by MitaniCorporation), an equivalent circle diameter (grain size) and a contentof Al₂O₃ were calculated. As a result, it was confirmed that in each ofsamples B17 to B24, the grain size of Al₂O₃ was 0.05 μm, and the contentthereof coincided with that of the raw material (30 volume %; theposition of presence thereof was in the crystal grain boundaries or thecrystal grains). In the sintered material of each of samples B17 to B24,the average grain size of the first material was 0.15 μm. Further, ineach of the sintered materials of samples B17 to B24, the average grainsize of the second material coincided with the average particle size ofthe raw material.

Then, for each of the sintered materials of samples B17 to B24, regionsof the first material and the second material were identified using areflected electron image obtained by measuring the CP-processed surfacewith the scanning electron microscope (SEM) or using element analysiswith Auger electron spectroscopy, and respective areas thereof weremeasured by a binarization process with the above-described imageanalysis software. Then, it could also be confirmed that: each sinteredmaterial included the first material and the second material; and theratio of the first material and the second material coincided with theraw material ratio.

<Samples B25 to B32>

The sintered materials of samples B25 to B32 are produced as follows.

(Production of First Material (Precursor) Used for Each of Samples B25to B30)

The first material (precursor) can be produced in accordance with thesame method as the method for producing the first material (precursor)used for sample A1. This first material (precursor) is partiallystabilized ZrO₂ in which 30 volume % of Al₂O₃ is dissolved in the solidstate with respect to the whole of the first material.

In each of samples B31 and B32, as described below, instead of using thefirst material (precursor) produced by the above-described method, acommercially available partially stabilized ZrO₂ powder (Trademark:“TZ-3Y” provided by TOSOH; average particle size of 45 nm) in whichAl₂O₃ was not dissolved in the solid state was prepared to be used.

(Preparation of Second Material)

The second material was prepared by obtaining a carbonitride powderusing the following method. Specifically, TiCN was mixed with TiC(grade: TiC-01; provided by Japan New Metals) and TiN (grade: TiN-01;provided by Japan New Metals) using a ball mill or a bead mill, therebyobtaining a mixture. ZrCN was mixed with ZrC (grade: ZrC—F; provided byJapan New Metals) and ZrN (grade: ZrN-01; provided by Japan New Metals)using a ball mill or a bead mill, thereby obtaining a mixture.

Then, each mixture was subjected to a heat treatment at 2000° C. in anAr atmosphere within a carbon furnace, and the heat-treated material wasthen pulverized using a carbide stick and a mill, thereby obtaining eachcarbonitride powder.

(Preparation of Third Phase)

As the raw material of the third phase, each of the followingcommercially available powders was prepared: Al₂O₃ powder (trademark:“TM-DAR” provided by Taimei Chemicals; average particle size of 0.1 μm);MgO powder (trademark: “FNM-G” provided by the Tateho ChemicalIndustries; average particle size of 0.5 μm); Ce₂O powder (trademark:“CE005PB” provided by Kojundo Chemical Laboratory; average particle sizeof 0.2 μm); Y₂O₃ powder (trademark: “YY003PB” provided by KojundoChemical Laboratory; average particle size of 0.4 μm); and HfO₂ powder(trademark: “HF001PB” provided by Kojundo Chemical Laboratory; averageparticle size of 2 μm).

Then, the first material (precursor), the second material constituted ofthe raw material powder shown in Table 3, and the third materialconstituted of the raw material powder shown in Table 3 were mixed usinga ball mill so as to attain a blending amount (volume %) shown in Table3, thereby obtaining a mixture of each sample. For each of samples B31and B32, a commercially available partially stabilized ZrO₂ powder inwhich Al₂O₃ was not dissolved in the solid state, the powder serving asthe raw material of the second material, and the powder serving as theraw material of the third phase were mixed using a ball mill so as toattain a blending amount (volume %) shown in Table 3, thereby obtaininga mixture.

Next, the mixtures of samples B25 to B32 were sintered for 15 minutes ata pressure of 7 GPa and a sintering temperature of 1400° C., therebyobtaining sintered materials of samples B25 to B32.

Each of the sintered materials of samples B25 to B32 was subjected to aCP process as described above, and a cross section thereof was observedwith the SEM, to thereby identify a position of presence of Al₂O₃ in thefirst material. In addition, by a binarization process with imageanalysis software (trademark: “WinROOF ver. 6.5.3” provided by MitaniCorporation), an equivalent circle diameter (grain size) and a contentof Al₂O₃ were calculated. As a result, it was confirmed that in each ofsamples B25 to B30, the grain size of Al₂O₃ was 0.05 μm, and the contentthereof coincided with that of the raw material (30 volume %; theposition of presence thereof was in the crystal grain boundaries or thecrystal grains). In the sintered material of each of samples B25 to B30,the average grain size of the first material was 0.15 μm. In each of thesintered materials of samples B31 and B32, the average grain size of thepartially stabilized ZrO₂ was 0.045 μm. Further, in each of the sinteredmaterials of samples B25 to B32, the average grain size of the secondmaterial coincided with the average particle size of the raw material.

Then, in each of the sintered materials of samples B25 to B32, areflected electron image obtained by measuring a CP-processed surfaceusing a scanning electron microscope (SEM), or an elemental analysis byAuger electron spectroscopy was employed to identify the region of thefirst material or partially stabilized ZrO₂ in which Al₂O₃ was notdissolved in the solid state, the region of the second material, and theregion of the third phase. Then, respective areas thereof were measuredby a binarization process with the above-described image analysissoftware. Accordingly, it could be confirmed that: each sinteredmaterial included the first material or the partially stabilized ZrO₂ inwhich Al₂O₃ was not dissolved in the solid state, the second material,and the third phase; and the ratio of these coincided with the ratio ofthe raw materials.

TABLE 3 First Material ATZ ATZ ATZ ATZ ATZ Sample 96 vol % 88 vol % 51vol % 30 vol % 0.6 vol % Second Material No. Al₂O₃ Al₂O₃ Al₂O₃ Al₂O₃Al₂O₃ ZrO₂ TiCN ZrCN NbCN TaCN B1 — — —  4 — — 96 — — — B2 — — — 10 — —90 — — — B3 — — — 40 — — 60 — — — B4 — — — 70 — — 30 — — — B5 — — — 90 —— 10 — — — B6 — — — 96 — —  4 — — — B7 — — — — — 70 30 — — — B8 — — —  4— — — 96 — — B9 — — — 10 — — — 90 — — B10 — — — 40 — — — 60 — — B11 — —— 70 — — — 30 — — B12 — — — 90 — — — 10 — — B13 — — — 96 — — —  4 — —B14 — — — — — 70 — 30 — — B15 — — — 40 — — — — 60 — B16 — — — 40 — — — —— 60 B17 40 — — — — — 60 — — — B18 — 40 — — — — 60 — — — B19 — — 40 — —— 60 — — — B20 — — — — 40 — 60 — — — B21 40 — — — — — — 60 — — B22 — 40— — — — — 60 — — B23 — — 40 — — — — 60 — — B24 — — — — 40 — — 60 — — B25— — — 10 — — 30 — — — B26 — — — 10 — — — 30 — — B27 — — — 10 — — 30 — —— B28 — — — 10 — — 30 — — — B29 — — — 10 — — 30 — — — B30 — — — 10 — —30 — — — B31 — — — — — 10 30 — — — B32 — — — — — 10 — 30 — — WearChipping State Sample Third Phase Amount After 10-km No. Al₂O₃ MgO Ce₂OY₂O₃ HfO₂ (μm) Processing Notes B1 — — — — — 103 C Too Large Amount ofTiCN B2 — — — — — 112 B B3 — — — — — 114 A B4 — — — — — 125 A B5 — — — —— 137 A B6 — — — — — 158 C Too Small Amount of TiCN B7 — — — — — 137 CNo ATZ B8 — — — — — 112 C Too Large Amount of ZrCN B9 — — — — — 122 BB10 — — — — — 125 A B11 — — — — — 134 A B12 — — — — — 148 A B13 — — — —— 165 C Too Large Amount of ZrCN B14 — — — — — 150 C No ATZ B15 — — — —— 154 B B16 — — — — — 149 B B17 — — — — — 103 C Too Large Amount ofAl₂O₃ B18 — — — — — 106 B B19 — — — — — 109 A B20 — — — — — 122 C TooSmall Amount of Al₂O₃ B21 — — — — — 110 C Too Large Amount of Al₂O₃ B22— — — — — 113 B B23 — — — — — 118 A B24 — — — — — 125 C Too Small Amountof Al₂O₃ B25 60 — — — — 102 A B26 60 — — — — 108 A B27 — 60 — — — 134 BB28 — — 60 — — 138 B B29 — — — 60 — 137 B B30 — — — — 60 132 B B31 60 —— — — 125 C No ATZ B32 60 — — — — 138 C No ATZ

<<Sintered Material Including Nitride as Second Material: Samples C1 toC34>>

As a raw material, the first material produced in the below-describedprocedure (neutralization co-precipitation method) was prepared. For thesecond material, a commercially available nitride powder was prepared.Further, in each of predetermined samples, a commercially availablepowder of a raw material to serve as the third phase was prepared asrequired.

<Samples C1 to C18>

Each of sintered materials of samples C1 to C18 is produced as follows.

(Production of First Material (Precursor))

The first material (precursor) can be produced in accordance with thesame method as the method for producing the first material (precursor)used for sample A1. This first material (precursor) is partiallystabilized ZrO₂ in which 30 volume % of Al₂O₃ is dissolved in the solidstate with respect to the whole of the first material.

Here, in each of samples C7 and C14 of samples C1 to C18, as describedbelow, instead of using the first material (precursor) produced by theabove-described method, a commercially available partially stabilizedZrO₂ powder (Trademark: “TZ-3Y” provided by TOSOH; average particle sizeof 45 nm) in which Al₂O₃ was not dissolved in the solid state wasprepared to be used.

(Preparation of Second Material)

For the second material, a commercially available nitride powder wasprepared. Specifically, as the second material, there were prepared: TiN(grade: TiN-01; provided by Japan New Metals); ZrN (grade: ZrN-01;provided by Japan New Metals); NbN (grade: NbN-0; provided by Japan NewMetals); TaN (grade: TaN-0 provided by Japan New Metals); Si₃N₄ (grade:SII09PB; provided by Kojundo Chemical Laboratory); and CrN (manufacturedin accordance with the manufacturing method disclosed in Japanese PatentLaying-Open No. 2002-241113). The particle size of the second materialwas 2 μm.

Then, the first material (precursor) was mixed with the second materialconstituted of the raw material powder shown in Table 4 using a ballmill so as to attain a blending amount (volume %) shown in Table 4,thereby obtaining a mixture of each sample. For each of samples C7 andC14, a commercially available partially stabilized ZrO₂ powder in whichAl₂O₃ was not dissolved in the solid state, and a powder serving as theraw material of the second material were mixed using a ball mill so asto attain a blending amount (volume %) shown in Table 4, therebyobtaining a mixture.

Next, the mixtures of samples C1 to C18 were sintered for 15 minutes ata pressure of 7 GPa and a sintering temperature of 1400° C., therebyobtaining sintered materials of samples C1 to C18.

Each of the sintered materials of samples C1 to C18 was subjected to aCP process as described above, and a cross section thereof was observedwith the SEM, to thereby identify a position of presence of Al₂O₃ in thefirst material. In addition, by a binarization process with imageanalysis software (trademark: “WinROOF ver. 6.5.3” provided by MitaniCorporation), an equivalent circle diameter (grain size) and a contentof Al₂O₃ were calculated. As a result, it was confirmed that in thesintered material of each of samples C1 to C6, C8 to C13, and C15 toC18, the grain size of Al₂O₃ was 0.05 μm, and the content thereofcoincided with that of the raw material (30 volume %; the position ofpresence thereof was in the crystal grain boundaries or the crystalgrains). In each of the sintered materials of samples C1 to C6, C8 toC13, and C15 to C18, the average grain size of the first material was0.15 μm. In each of the sintered materials of samples C7 and C14, theaverage grain size of the partially stabilized ZrO₂ was 0.1 μm. Further,in each of the sintered materials of samples C1 to C18, the averagegrain size of the second material coincided with the average particlesize of the raw material.

Then, in each of the sintered materials of samples C1 to C18, areflected electron image obtained by measuring a CP-processed surfaceusing a scanning electron microscope (SEM), or an elemental analysis byAuger electron spectroscopy was employed to identify the region of thefirst material or partially stabilized ZrO₂ in which Al₂O₃ was notdissolved in the solid state, and the region of the second material.Then, respective areas thereof were measured by a binarization processwith the above-described image analysis software. Accordingly, it couldbe confirmed that: each sintered material included the first material orthe partially stabilized ZrO₂ in which Al₂O₃ was not dissolved in thesolid state, and the second material; and the ratio of these coincidedwith the ratio of the raw materials.

<Samples C19 to C26>

Each of sintered materials of samples C19 to C26 is produced as follows.

(Production of First Material (Precursor) Used for Each of Samples C19and C23)

The first material can be produced in accordance with the same method asthe method for producing the first material (precursor) used for sampleA27. This first material (precursor) is partially stabilized ZrO₂ inwhich 96 volume % of Al₂O₃ is dissolved in the solid state with respectto the whole of the first material.

(Production of First Material (Precursor) Used for Each of Samples C20and C24)

The first material (precursor) can be produced in accordance with thesame method as the method for producing the first material (precursor)used for sample A28. This first material (precursor) is partiallystabilized ZrO₂ in which 88 volume % of Al₂O₃ is dissolved in the solidstate with respect to the whole of the first material.

(Production of First Material (Precursor) Used for Each of Samples C21and C25)

The first material (precursor) can be produced in accordance with thesame method as the method for producing the first material (precursor)used for sample A29. This first material (precursor) is partiallystabilized ZrO₂ in which 51 volume % of Al₂O₃ is dissolved in the solidstate with respect to the whole of the first material.

(Production of First Material (Precursor) Used for Each of Samples C22and C26)

The first material (precursor) can be produced in accordance with thesame method as the method for producing the first material (precursor)used for sample A30. This first material (precursor) is partiallystabilized ZrO₂ in which 0.6 volume % of Al₂O₃ is dissolved in the solidstate with respect to the whole of the first material.

(Preparation of Second Material)

For the second material, a commercially available nitride powder wasprepared. Specifically, as the second material, TiN (grade: TiN-01;provided by Japan New Metals) and ZrN (grade: ZrN-01; provided by JapanNew Metals) were prepared. The particle size of the second material was2 μm.

Then, the first material (precursor) was mixed with the second materialconstituted of the raw material powder shown in Table 4 using a ballmill so as to attain a blending amount (volume %) shown in Table 4,thereby obtaining a mixture of each sample.

Next, the mixtures of samples C19 to C26 were sintered for 15 minutes ata pressure of 7 GPa and a sintering temperature of 1400° C., therebyobtaining sintered materials of samples C19 to C26.

Each of the sintered materials of samples C19 to C26 was subjected to aCP process as described above, and a cross section thereof was observedwith the SEM, to thereby identify a position of presence of Al₂O₃ in thefirst material. In addition, by a binarization process with imageanalysis software (trademark: “WinROOF ver. 6.5.3” provided by MitaniCorporation), an equivalent circle diameter (grain size) and a contentof Al₂O₃ were calculated. As a result, it was confirmed that in each ofsamples C19 to C26, the grain size of Al₂O₃ was 0.05 μm, and the contentthereof coincided with that of the raw material (30 volume %; theposition of presence thereof was in the crystal grain boundaries or thecrystal grains). In the sintered material of each of samples C19 to C26,the average grain size of the first material was 0.15 μm. Further, ineach of the sintered materials of samples C19 to C26, the average grainsize of the second material coincided with the average particle size ofthe raw material.

In addition, for the sintered materials of samples C19 to C26, regionsof the first material and the second material were identified using areflected electron image obtained by measuring the CP-processed surfacewith the scanning electron microscope (SEM) or using element analysiswith Auger electron spectroscopy, and respective areas thereof weremeasured by a binarization process with the above-described imageanalysis software. Then, it could also be confirmed that: each sinteredmaterial included the first material and the second material; and theratio of the first material and the second material coincided with theratio of the raw materials.

<Samples C27 to C34>

The sintered materials of samples C27 to C34 are produced as follows.

(Production of First Material (Precursor) Used for Each of Samples C27to C32)

The first material (precursor) can be produced in accordance with thesame method as the method for producing the first material (precursor)used for sample A1. This first material (precursor) is partiallystabilized ZrO₂ in which 30 volume % of Al₂O₃ is dissolved in the solidstate with respect to the whole of the first material.

In each of samples C33 and C34, as described below, instead of using thefirst material (precursor) produced by the above-described method, acommercially available partially stabilized ZrO₂ powder (Trademark:“TZ-3Y” provided by TOSOH; average particle size of 45 nm) in whichAl₂O₃ was not dissolved in the solid state was prepared to be used.

(Preparation of Second Material)

For the second material, a commercially available nitride powder wasprepared. Specifically, TiN (grade: TiN-01; provided by Japan NewMetals) and ZrN (grade: ZrN-01; provided by Japan New Metals) wereprepared as the second material. The particle size of the secondmaterial was 2 μm.

(Preparation of Third Phase)

Each of the following commercially available powders was prepared as theraw material of the third phase: Al₂O₃ powder (trademark: “TM-DAR”provided by Taimei Chemicals; average particle size of 0.1 μm); MgOpowder (trademark: “FNM-G” provided by Tateho Chemical Industries;average particle size of 0.5 μm); Ce₂O powder (trademark: “CE005PB”provided by Kojundo Chemical Laboratory; average particle size of 0.2μm); Y₂O₃ powder (trademark: “YY003PB” provided by Kojundo ChemicalLaboratory; average particle size of 0.4 μm); and HfO₂ powder(trademark: “HF001PB” provided by Kojundo Chemical Laboratory; averageparticle size of 2 μm).

Then, the first material (precursor), the second material constituted ofthe raw material powder shown in Table 4, and the third materialconstituted of the raw material powder shown in Table 4 were mixed usinga ball mill so as to attain a blending amount (volume %) shown in Table4, thereby obtaining a mixture of each sample. For each of samples C33and C34, the commercially available partially stabilized ZrO₂ powder inwhich Al₂O₃ was not dissolved in the solid state, the powder serving asthe raw material of the second material, and the powder serving as theraw material of the third phase were mixed using a ball mill so as toattain a blending amount (volume %) shown in Table 4, thereby obtaininga mixture.

Next, the mixtures of samples C27 to C34 were sintered for 15 minutes ata pressure of 7 GPa and a sintering temperature of 1400° C., therebyobtaining sintered materials of samples C27 to C34.

Each of the sintered materials of samples C27 to C34 was subjected to aCP process as described above, and a cross section thereof was observedwith the SEM, to thereby identify a position of presence of Al₂O₃ in thefirst material. In addition, by a binarization process with imageanalysis software (trademark: “WinROOF ver. 6.5.3” provided by MitaniCorporation), an equivalent circle diameter (grain size) and a contentof Al₂O₃ were calculated. As a result, it was confirmed that in thesintered material of each of samples C27 to C32, the grain size of Al₂O₃was 0.05 μm, and the content thereof coincided with that of the rawmaterial (30 volume %; the position of presence thereof was in thecrystal grain boundaries or the crystal grains). In the sinteredmaterial of each of samples C27 to C32, the average grain size of thefirst material was 0.15 μm. In each of the sintered materials of samplesC33 and C34, the average grain size of the partially stabilized ZrO₂ was0.1 μm. Further, in each of the sintered materials of samples C27 toC34, the average grain size of the second material coincided with theaverage particle size of the raw material.

Then, in each of the sintered materials of samples C27 to C34, areflected electron image obtained by measuring a CP-processed surfaceusing a scanning electron microscope (SEM), or an elemental analysis byAuger electron spectroscopy was employed to identify the region of thefirst material or partially stabilized ZrO₂ in which Al₂O₃ was notdissolved in the solid state, the region of the second material, and theregion of the third phase. Then, respective areas thereof were measuredby a binarization process with the above-described image analysissoftware. Accordingly, it could be confirmed that: each sinteredmaterial included the first material or the partially stabilized ZrO₂ inwhich Al₂O₃ was not dissolved in the solid state, the second material,and the third phase; and the ratio of these coincided with the ratio ofthe raw materials.

TABLE 4 First Material ATZ ATZ ATZ ATZ ATZ Sample 96 vol % 88 vol % 51vol % 30 vol % 0.6 vol % Second Material No. Al₂O₃ Al₂O₃ Al₂O₃ Al₂O₃Al₂O₃ ZrO₂ TiN ZrN NbN TaN CrN Si₃N₄ C1 — — —  4 — — 96 — — — — — C2 — —— 10 — — 90 — — — — — C3 — — — 40 — — 60 — — — — — C4 — — — 70 — — 30 —— — — — C5 — — — 90 — — 10 — — — — — C6 — — — 96 — —  4 — — — — — C7 — —— — — 70 30 — — — — — C8 — — —  4 — — — 96 — — — — C9 — — — 10 — — — 90— — — — C10 — — — 40 — — — 60 — — — — C11 — — — 70 — — — 30 — — — — C12— — — 90 — — — 10 — — — — C13 — — — 96 — — —  4 — — — — C14 — — — — — 70— 30 — — — — C15 — — — 40 — — — — 60 — — — C16 — — — 40 — — — — — 60 — —C17 — — — 40 — — — — — — 60 — C18 — — — 40 — — — — — — — 60 C19 40 — — —— — 60 — — — — — C20 — 40 — — — — 60 — — — — — C21 — — 40 — — — 60 — — —— — C22 — — — — 40 — 60 — — — — — C23 40 — — — — — — 60 — — — — C24 — 40— — — — — 60 — — — — C25 — — 40 — — — — 60 — — — — C26 — — — — 40 — — 60— — — — C27 — — — 10 — — 30 — — — — — C28 — — — 10 — — — 30 — — — — C29— — — 10 — — 30 — — — — — C30 — — — 10 — — 30 — — — — — C31 — — — 10 — —30 — — — — — C32 — — — 10 — — 30 — — — — — C33 — — — — — 10 30 — — — — —C34 — — — — — 10 — 30 — — — — Wear Chipping State Sample Third PhaseAmount After 10-km No. Al₂O₃ MgO Ce₂O Y₂O₃ HfO₂ (μm) Processing Notes C1— — — — — 105 C Large Amount of TiN C2 — — — — — 114 B C3 — — — — — 116A C4 — — — — — 127 A C5 — — — — — 139 A C6 — — — — — 160 C Too SmallAmount of TiN C7 — — — — — 139 C No ATZ C8 — — — — — 114 C Too LargeAmount of ZrN C9 — — — — — 124 B C10 — — — — — 127 A C11 — — — — — 136 AC12 — — — — — 150 A C13 — — — — — 167 C Too Small Amount of ZrN C14 — —— — — 152 C No ATZ C15 — — — — — 156 B C16 — — — — — 151 B C17 — — — — —170 B C18 — — — — — 163 B C19 — — — — — 105 C Too Large Amount of Al₂O₃C20 — — — — — 108 B C21 — — — — — 111 A C22 — — — — — 124 C Too SmallAmount of Al₂O₃ C23 — — — — — 112 C Too Large Amount of Al₂O₃ C24 — — —— — 115 B C25 — — — — — 120 A C26 — — — — — 127 C Too Small Amount ofAl₂O₃ C27 60 — — — — 104 A C28 60 — — — — 110 A C29 — 60 — — — 136 B C30— — 60 — — 140 B C31 — — — 60 — 139 B C32 — — — — 60 134 B C33 60 — — —— 127 C No ATZ C34 60 — — — — 140 C No ATZ

<<Sintered Material Including Two Types of Carbides as Second Material:Samples D1 to D14>>

As a raw material, the first material produced in the below-describedprocedure (neutralization co-precipitation method) was prepared. For thesecond material, a commercially available carbide powder was prepared.Further, in each of predetermined samples, a commercially availablepowder of a raw material to serve as the third phase was prepared asrequired. Specifically, the sintered materials of samples D1 to D14 areproduced as follows.

(Production of First Material (Precursor) Used for Each of Samples D1and D8)

The first material (precursor) can be produced in accordance with thesame method as the method for producing the first material (precursor)used for sample A27. This first material (precursor) is partiallystabilized ZrO₂ in which 96 volume % of Al₂O₃ is dissolved in the solidstate with respect to the whole of the first material.

(Production of First Material (Precursor) Used for Each of Samples D2and D9)

The first material (precursor) can be produced in accordance with thesame method as the method for producing the first material (precursor)used for sample A28. This first material (precursor) is partiallystabilized ZrO₂ in which 88 volume % of Al₂O₃ is dissolved in the solidstate with respect to the whole of the first material.

(Production of First Material (Precursor) Used for Each of Samples D3and D10)

The first material (precursor) can be produced in accordance with thesame method as the method for producing the first material (precursor)used for sample A29. This first material (precursor) is partiallystabilized ZrO₂ in which 51 volume % of Al₂O₃ is dissolved in the solidstate with respect to the whole of the first material.

(Production of First Material (Precursor) Used for Each of Samples D4,D6, D11, and D13)

The first material (precursor) can be produced in accordance with thesame method as the method for producing the first material (precursor)used for sample A1. This first material (precursor) is partiallystabilized ZrO₂ in which 30 volume % of Al₂O₃ is dissolved in the solidstate with respect to the whole of the first material.

(Production of First Material (Precursor) Used for Each of Samples D5and D12)

The first material (precursor) can be produced in accordance with thesame method as the method for producing the first material (precursor)used for sample A30. This first material (precursor) is partiallystabilized ZrO₂ in which 0.6 volume % of Al₂O₃ is dissolved in the solidstate with respect to the whole of the first material.

Here, in each of samples D7 and D14 of samples D1 to D14, as describedbelow, instead of using the first material (precursor) produced by theabove-described method, a commercially available partially stabilizedZrO₂ powder (Trademark: “TZ-3Y” provided by TOSOH; average particle sizeof 45 nm) in which Al₂O₃ was not dissolved in the solid state wasprepared to be used.

(Preparation of Second Material)

For the second material, commercially available carbide powders wereprepared. Specifically, as the second material, TiC (grade: TiC-01;provided by Japan New Metals), ZrC (grade: ZrC—F; provided by Japan NewMetals), and WC (grade: WWI14PBWC; provided by Kojundo ChemicalLaboratory) were prepared. The particle size of the second material was2 μm.

(Preparation of Third Phase)

The following commercially available powder was prepared as the rawmaterial of the third phase: Al₂O₃ powder (trademark: “TM-DAR” providedby Taimei Chemicals; average particle size of 0.1 μm).

Then, the first material (precursor) was mixed with the second materialconstituted of the raw material powder shown in Table 5 using a ballmill so as to attain a blending amount (volume %) shown in Table 5,thereby obtaining a mixture of each sample. For each of samples D6 andD13, the first material (precursor), the powder serving as the rawmaterial of the second material, and the powder serving as the rawmaterial of the third phase were mixed using a ball mill so as to attaina blending amount (volume %) shown in Table 5, thereby obtaining amixture. For each of samples D7 and D14, a commercially availablepartially stabilized ZrO₂ powder in which Al₂O₃ was not dissolved in thesolid state, the powder serving as the raw material of the secondmaterial, and the powder serving as the raw material of the third phasewere mixed using a ball mill so as to attain a blending amount (volume%) shown in Table 5, thereby obtaining a mixture.

Next, the mixtures of samples D1 to D14 were sintered for 15 minutes ata pressure of 7 GPa and a sintering temperature of 1400° C., therebyobtaining sintered materials of samples D1 to D14.

Each of the sintered materials of samples D1 to D14 was subjected to aCP process as described above, and a cross section thereof was observedwith the SEM, to thereby identify a position of presence of Al₂O₃ in thefirst material. In addition, by a binarization process with imageanalysis software (trademark: “WinROOF ver. 6.5.3” provided by MitaniCorporation), an equivalent circle diameter (grain size) and a contentof Al₂O₃ were calculated. As a result, it was confirmed that in thesintered material of each of samples D1 to D6 and D8 to D13, the grainsize of Al₂O₃ was 0.05 μm, and the content thereof coincided with thatof the raw material (30 volume %; the position of presence thereof wasin the crystal grain boundaries or the crystal grains). In the sinteredmaterial of each of samples D1 to D6 and D8 to D13, the average grainsize of the first material was 0.15 μm. In each of the sinteredmaterials of samples D7 and D14, the average grain size of the partiallystabilized ZrO₂ was 0.045 μm. Further, in each of the sintered materialsof samples D1 to D14, the average grain size of the second materialcoincided with the average particle size of the raw material.

Then, in each of the sintered materials of samples D1 to D14, areflected electron image obtained by measuring a CP-processed surfaceusing a scanning electron microscope (SEM), or an elemental analysis byAuger electron spectroscopy was employed to identify the region of thefirst material or partially stabilized ZrO₂ in which Al₂O₃ was notdissolved in the solid state, the region of the second material, and, inthe case of samples D6, D7, D13, and D14, the region of the third phase.Then, respective areas thereof were measured by a binarization processwith the above-described image analysis software. Accordingly, it couldbe confirmed that: each sintered material included the first material orthe partially stabilized ZrO₂ in which Al₂O₃ was not dissolved in thesolid state, the second material, and, in the case of samples D6, D7,D13, and D14, the third phase; and the ratio of these coincided with theratio of the raw materials.

TABLE 5 First Material ATZ ATZ ATZ ATZ ATZ 96 88 51 30 0.6 ThirdChipping State Sample vol % vol % vol % vol % vol % Second MaterialPhase Wear Amount After 10-km No. Al₂O₃ Al₂O₃ Al₂O₃ Al₂O₃ Al₂O₃ ZrO₂ TiCZrC WC Al₂O₃ (μm) Processing Notes D1 20 — — — — — 40 — 40 — 105 C TooLarge Amount of Al₂O₃ D2 — 20 — — — — 40 — 40 — 110 B D3 — — 20 — — — 40— 40 — 115 A D4 — — — 20 — — 40 — 40 — 121 A D5 — — — — 20 — 40 — 40 —126 C Too Small Amount of Al₂O₃ D6 — — — 20 — — 40 — 40 20 104 A D7 — —— — — 20 40 — 40 20 135 C No ATZ D8 20 — — — — — — 40 40 — 108 C TooLarge Amount of Al₂O₃ D9 — 20 — — — — — 40 40 — 113 B D10 — — 20 — — — —40 40 — 118 A D11 — — — 20 — — — 40 40 — 124 A D12 — — — — 20 — — 40 40— 129 C Too Small Amount of Al₂O₃ D13 — — — 20 — — — 40 40 20 107 A D14— — — — — 20 — 40 40 20 138 C No ATZ

(Cutting Test)

Next, the sintered material of each of samples A1 to A48, samples B1 toB32, samples C1 to C34, and samples D1 to D14 was used to produce acutting tool having the following shape: CNMA120408; a chamfer angle of15°; and a chamfer width of 0.12 mm. Then, the sintered material wassubjected to a cutting test using a NC lathe to perform high-speedstrong interrupted cutting under the following cutting conditions.

Workpiece: carburized and quenched steel (SCM415-5V, HRC: 62)

Shape of the workpiece: cylindrical shape (outer diameter ϕ of 100mm×length of 300 mm; five V grooves provided in the axial direction)

Cutting speed: V=130 m/min.

Feed: f=0.1 mm/rev.

Depth of cut: ap=0.2 mm

Wet type/dry type: dry type.

(Evaluation of Cutting)

In each of the cutting tools of samples A1 to A48, samples B1 to B32,samples C1 to C34, and samples D1 to D14, a flank wear amount (μm) upon3-km cutting was measured (evaluated in wear resistance). Further, ineach of these cutting tools, a chipping state upon 10-km cutting wasobserved (evaluated in chipping resistance). Regarding the chippingstate, A represents a state in which there was no chipping in thecutting tool, B represents a state in which there was minute chippingbut the cutting edge thereof remained, and C represents a state in whichthe cutting edge thereof ceased to exist due to chipping. Results areshown in Table 1 to Table 5. In this cutting test, the carburized andquenched steel was used as the workpiece; however, the workpiece shouldnot be limited to this. Examples of the workpiece usable herein include:gray iron; a heat-resistant alloy such as Inconel®; various types ofsteels; and the like.

In the cutting tool composed of the sintered material of each of samplesA2 to A5, A10 to A13, A17 to A20, A23 to A26, A28 to A29, A32 to A33,A36 to A37, and A39 to A45, the first material is partially stabilizedZrO₂ in which 1 to 90 volume % of Al₂O₃ is dispersed in crystal grainboundaries or crystal grains, the second material is a carbide, 5 to 95volume % of the second material is included in the sintered material,and the grain size of Al₂O₃ is less than or equal to 1 μm. As apparentfrom Table 1 and Table 2, each of these cutting tools had a small flankface wear amount upon the 3-km cutting and was therefore excellent inwear resistance, and also had an excellent chipping state upon the 10-kmcutting and was therefore excellent in chipping resistance. Among theabove-described cutting tools, the chipping states upon the 10-kmcutting were particularly excellent in cutting tools in each of whichthe volume ratio, ZrO₂/(ZrO₂+Al₂O₃), in the first material was more thanor equal to 0.49.

In each of the cutting tools composed of the sintered materials ofsamples B2 to B5, B9 to B12, B15 to B16, B18 to B19, B22 to B23, and B25to B30, the first material is partially stabilized ZrO₂ in which 1 to 90volume % of Al₂O₃ is dispersed in crystal grain boundaries or crystalgrains, the second material is a carbonitride, 5 to 95 volume % of thesecond material is included in the sintered material, and the grain sizeof Al₂O₃ is less than or equal to 1 μm. As apparent from Table 3, eachof these cutting tools had a small flank face wear amount upon the 3-kmcutting and was therefore excellent in wear resistance, and also had anexcellent chipping state upon the 10-km cutting and was thereforeexcellent in chipping resistance. Among the above-described cuttingtools, the chipping states upon the 10-km cutting were particularlyexcellent in cutting tools in each of which the volume ratio,ZrO₂/(ZrO₂+Al₂O₃), in the first material was more than or equal to 0.49.

In the each of the cutting tools composed of the sintered materials ofsamples C2 to C5, C9 to C12, C15 to C18, C20 to C21, C24 to C25, and C27to C32, the first material is partially stabilized ZrO₂ in which 1 to 90volume % of Al₂O₃ is dispersed in crystal grain boundaries or crystalgrains, the second material is a nitride, 5 to 95 volume % of the secondmaterial is included in the sintered material, and the grain size ofAl₂O₃ is less than or equal to 1 μm. As apparent from Table 4, each ofthese cutting tools had a small flank face wear amount upon the 3-kmcutting and was therefore excellent in wear resistance, and also had anexcellent chipping state upon the 10-km cutting and was thereforeexcellent in chipping resistance. Among the above-described cuttingtools, the chipping states upon the 10-km cutting were particularlyexcellent in cutting tools in each of which the volume ratio,ZrO₂/(ZrO₂+Al₂O₃), in the first material was more than or equal to 0.49.

In each of the cutting tools composed of the sintered materials ofsamples D2 to D4, D6, D9 to D11, and D13, the first material ispartially stabilized ZrO₂ in which 1 to 90 volume % of Al₂O₃ isdispersed in crystal grain boundaries or crystal grains, the secondmaterial is the two types of carbides, 5 to 95 volume % of the secondmaterial is included in the sintered material, and the grain size ofAl₂O₃ is less than or equal to 1 μm. As apparent from Table 5, each ofthese cutting tools had a small flank face wear amount upon the 3-kmcutting and was therefore excellent in wear resistance, and also had anexcellent chipping state upon the 10-km cutting and was thereforeexcellent in chipping resistance. Among the above-described cuttingtools, the chipping states upon the 10-km cutting were particularlyexcellent in cutting tools in each of which the volume ratio,ZrO₂/(ZrO₂+Al₂O₃), in the first material was more than or equal to 0.49.

Heretofore, the embodiments and examples of the present invention havebeen illustrated, but it has been initially expected to appropriatelycombine the configurations of the embodiments and examples and modifythem in various manners.

The embodiments and examples disclosed herein are illustrative andnon-restrictive in any respect. The scope of the present invention isdefined by the terms of the claims, rather than the embodimentsdescribed above, and is intended to include any modifications within thescope and meaning equivalent to the terms of the claims.

1. A sintered material comprising a first material and a secondmaterial, wherein the first material is partially stabilized ZrO₂ inwhich 1 to 90 volume % of Al₂O₃ is dispersed in crystal grain boundariesor crystal grains, the Al₂O₃ is a grain having a grain size of less thanor equal to 1 μm, and the second material is at least one compoundselected from a group consisting of a carbide, a nitride, and acarbonitride, and 5 to 95 volume % of the second material is included inthe sintered material.
 2. The sintered material according to claim 1,wherein the compound includes at least one element selected from a groupconsisting of a group 4 element, a group 5 element, a group 6 element,and Si in a periodic table.
 3. The sintered material according to claim1, wherein a volume ratio, ZrO₂/(ZrO₂+Al₂O₃), in the first material ismore than or equal to 0.49.
 4. The sintered material according to claim1, wherein the sintered material further includes a third phase, thethird phase includes at least one selected from a group consisting ofaluminum oxide, magnesium oxide, cerium oxide, yttrium oxide, andhafnium oxide, and less than or equal to 95 volume % of the third phaseis included in the sintered material.
 5. A cutting tool comprising thesintered material recited in claim 1.